China is the world's largest producer and consumer of peanut with a peanut yield of 16.44 million tones in 2015, which accounts for about 40.77% of the world's total yield. 50% to 65% of the total peanut yield is used for oil preparation. Defatted peanut cake (meal) is a by-product obtained after pression or extraction of peanut for oil preparation, in which the protein content is up to 50%-70% (dry basis). It is estimated that about 3 million or more tons of peanut cake (meal) per year need to be developed and utilized in China, which can be converted into 1.5 million or more tons of peanut protein and becomes the third largest vegetable protein source in China after wheat and soybean. For a long time, due to backward traditional oil-producing technologies, proteins in defatted peanut meal are seriously denatured, and thus the defatted peanut meal is unfit for consumption and can only be used as feed or fertilizer, resulting in a huge waste of protein resources. In recent years, with the increasing emphasis on peanut proteins, low denatured peanut proteins of high quality with a nitrogen soluble index of 70% or more can be obtained while high-quality peanut oil is obtained by improving traditional oil-producing technologies and using oil-producing technologies such as low-temperature pressing method, low temperature prepressing-water dissolving method, aqueous enzymatic extraction method, high-efficiency extraction method and the like. At present, peanut protein products are mainly divided into three types: peanut protein powder, peanut protein concentrate and peanut protein isolate. Peanut protein powder has a bright white color and a digestibility coefficient of up to 90%, also does not have cholesterol and flatulence factors, and its characteristic amino acid, arginine, has the effect of anti-aging. Therefore, the peanut protein powder is of great development and utilization value.
Food extrusion technology is one of the most important food-processing technologies, in which processes such as mixing, stirring, crushing, heating, cooking, puffing and molding and the like are integrated, and it has the features such as high efficiency, low energy consumption, low emission, low cost, high-temperature short-time, less nutrient loss and the like. The use of the extrusion technology in food production has a history of more than 70 years, wherein, production of texturized vegetable protein (TVP) using vegetable proteins such as soybean protein, peanut protein, gluten protein, whey protein and the like as main raw materials is an important application of the extrusion technology in the food industry. The TVP produced by the extrusion method has excellent functional properties such as water absorption, oil absorption and the like, a cholesterol content of zero, and a function of preventing “modern civilization diseases” such as hypertension, obesity, cardiovascular and cerebrovascular diseases and the like; and it can be used as additive of meat products or meat analogues for human consumption. The TVP can be divided into high-protein TVP (the protein content is higher than 70%) and low-protein texturized protein (the protein content is between 50% and 55%) according to the protein content in raw materials; can be divided into low-moisture TVP (the moisture content is lower than 35%) and high-moisture TVP (the moisture content is higher than 45%) according to the moisture content; and can be divided into ordinary TVP (having a small amount of fibrous structures) and fibrous TVP (having an obvious fibrous structure) according to the fibrous structure of the products. Ordinary low-moisture TVP is the main product form in the international and domestic markets. High-moisture TVP is a kind of new product, and, based on analysis of its organizational structure and texture, it has more excellent properties as compared with puffed product. The high-moisture TVP has a longer fiber length, a more delicate structure, a more uniform texture, and higher elasticity and tenacity, which can be eaten directly and is an upgrading product of the puffed product.
A Chinese patent titled “Method for producing TPP by utilizing hot-pressed peanut cake (meal)” (Publication No. CN102028094A) discloses a method for preparing puffed TPP using hot-pressed peanut cake (meal) as a raw material. Although nutritive materials belonging to the class of vitamin are added during the processing, the nutrients in peanuts are seriously destroyed in the subsequent high temperature drying process. A Chinese patent titled “Fibrous TVP and a preparation method thereof” (Publication No. CN102028095A) discloses a method for preparing a low-moisture fibrous TVP using grain protein, protein isolate and starch as the raw materials and an extruder provided with an outlet mould for form the fibrous structure, wherein, after rehydration, the fibrous TVP has appearance and characteristics similar to animal muscles, and can be torn into strips. However, the prepared product needs to be rehydrated for consumption, the fibrous structure is not abundant, and it is mainly used as an additive for meat products. A Chinese patent titled “Method for producing ready-to-eat vegetarian meat by using soybean protein isolate” (Publication No. CN101889627A) discloses a method for producing high-moisture texturized soybean protein (TSP) using soybean protein isolate. However, the soybean protein isolate has a high manufacturing cost and contains flatulence factors; and the TVP product has a beany flavor, which reduces the consumer acceptability.
In view of this, the present invention has been proposed.